Can be done, we made a guide to do it

Polycom IP5000

Single Call
Press “New Call”
Dial 9 + number
Press send.

Conference Call (2 Callers + the conference unit)
Press “New Call”, Dial 9 + number, Press Send (wait for caller to answer)
Press Hold
Press New Call, Dial 46 Press Send wait for call to clear
Press New Call, Dial 9 + Number, Press Send (wait for caller to answer)
Press Hold
Press New Call, Dial 46 Press Send
Press Resume to join the calls together.

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